Drive torque estimation device for compressor and condenser used for the device

Abstract

A drive torque estimation device secures accuracy of a drive torque of a compressor by accurately grasping a flow rate of refrigerant in a cycle. The pressure difference is detected by a condenser as a resistor for calculating the flow rate. The pressure difference between two portions based on physical quantities relating to refrigerant pressures is detected using first and second sensors arranged at two portions in the cycle. A flow rate is calculated based on the detected pressure difference. The first sensor may be an upstream-side pressure sensor arranged at an inlet of the condenser or at a high-pressure side pipe upstream of the inlet and detects a pressure of the refrigerant flowing therethrough, and the second sensor may be a downstream-side pressure sensor arranged at a gas/liquid mixed phase region of the condenser and detects a pressure of the refrigerant flowing therethrough or may be a temperature sensor.

What is claimed is: 
     
       1. A drive torque estimation device which calculates an estimated value of a drive torque of a compressor using a flow rate of a refrigerant which flows in a refrigerating cycle including the compressor, a condenser, an expansion device and an evaporator as one of variable parameters comprising: a first sensor which detects a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion of the refrigerating cycle; and a second sensor which detects a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion downstream of the first sensor in the refrigerating cycle, the flow rate of the refrigerant being calculated based on the difference between refrigerant pressures obtained based on the respective physical quantities detected by the first and second sensors, wherein
 the first sensor is arranged at a refrigerant inlet of the condenser or at a high-pressure side pipe upstream of the refrigerant inlet, and 
 the second sensor is arranged at a predetermined portion of the condenser which avoids a region where a liquid-phase refrigerant is present and becomes a gas/liquid mixed phase region. 
 
     
     
       2. The drive torque estimation device for a compressor according to  claim 1 , wherein the condenser includes a condensing part which condenses a passing refrigerant and a supercooling part which is communicated with the condensing part through a gas/liquid separation part and cools a liquid-phase refrigerant, and
 the second sensor is arranged at an outlet of the condensing part. 
 
     
     
       3. The drive torque estimation device according to  claim 2 , wherein the second sensor is arranged at an outlet of the condensing part. 
     
     
       4. The drive torque estimation device for a compressor according to  claim 1 , wherein a plurality of second sensors are arranged along a refrigerant flow passage of the condenser, and
 the drive torque estimation device includes a means which selects a sensor to be used corresponding to an outside air temperature. 
 
     
     
       5. The drive torque estimation device according to  claim 4 , wherein the drive torque estimation device includes a means which selects the second sensor to be used corresponding to an outside air temperature. 
     
     
       6. The drive torque estimation device for a compressor according to  claim 1 , wherein the second sensor is a temperature sensor which detects a refrigerant temperature at a predetermined portion of the condenser which becomes a gas/liquid mixed phase region. 
     
     
       7. The drive torque estimation device for a compressor according to  claim 1 , wherein in a state where a refrigerant pressure in a high-pressure-side path of the refrigerating cycle is balanced after the refrigerating cycle is stopped, an output value of the first sensor and an output value of the second sensor are calibrated such that the output value of the first sensor and the output value of the second sensor take the same value. 
     
     
       8. A condenser used in a refrigerating cycle which condenses a refrigerant which flows in a refrigerant flow passage by cooling, the condenser comprising:
 a first sensor which detects a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion of the refrigerant flow passage; and 
 a second sensor which detects a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion downstream of the first sensor in the refrigerant flow passage, wherein 
 the first sensor is arranged at a refrigerant inlet of the refrigerant flow passage, and the second sensor is arranged at a predetermined portion of the refrigerant flow passage which avoids a region where a liquid-phase refrigerant is present and becomes a gas/liquid mixed phase region. 
 
     
     
       9. The condenser according to  claim 8 , wherein the condenser includes a condensing part which condenses a passing refrigerant and a supercooling part which is communicated with the condensing part through a gas/liquid separation part and cools a liquid-phase refrigerant, and
 the second sensor is arranged at an outlet of the condensing part. 
 
     
     
       10. The condenser according to  claim 9 , wherein the second sensor is arranged at an outlet of the condensing part. 
     
     
       11. The condenser according to  claim 8 , wherein a plurality of second sensors are arranged along a refrigerant flow passage. 
     
     
       12. The condenser according to  claim 8 , wherein the second sensor is a temperature sensor which detects a refrigerant temperature at a predetermined portion of the refrigerant flow passage which becomes a gas/liquid mixed phase region. 
     
     
       13. A method of calculating an estimated value of a drive torque of a compressor comprising:
 providing a refrigerating cycle including the compressor, a condenser, an expansion device and an evaporator; 
 providing a refrigerant which flows through the refrigerating cycle; 
 detecting, with a first sensor, a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion of the refrigerating cycle; 
 detecting, with a second sensor, a physical quantity relating to a pressure of the refrigerant which flows through a predetermined portion downstream of the first sensor in the refrigerating cycle; 
 calculating a flow rate of the refrigerant based on the difference between refrigerant pressures obtained based on the respective physical quantities detected by the first and second sensors, wherein the first sensor is arranged at a refrigerant inlet of the condenser or at a high-pressure side pipe upstream of the refrigerant inlet, and the second sensor is arranged at a predetermined portion of the condenser which becomes a gas/liquid mixed phase region. 
 
     
     
       14. The method according to  claim 13 , wherein the physical quantities detected by the second sensor are detected outside a liquid-phase region of the condenser.